Bilateral prism

I recently saw a presentation relating to a new appliance aimed at those with macular degeneration. The lenses had a yellow filter which I agreed might enhance contrast for many patients. However, the lenses also had bilateral vertical prism (same direction, same amount) included to encourage eccentric viewing.

Now maybe I am being a bit slow here, but I fail to see how bilateral prism will do anything other than alter the bilateral gaze position but still, without appropriate training and target location, change the centration of the scotoma. Anyone able to convince me otherwise?